Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 231402 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 10 AM EDT TUE SEP 23 2014 .SYNOPSIS...
-- Changed Discussion --
A STALLED UPPER LEVEL LOW AND ATTENDANT COASTAL LOW PRESSURE SYSTEM WILL LINGER OVER THE CAROLINAS THROUGH WEDNESDAY... THEN TRACK UP THE MID-ATLANTIC COAST WEDNESDAY NIGHT. HIGH PRESSURE WILL EXTEND SOUTHWARD INTO THE REGION ON THURSDAY AND FRIDAY.
-- End Changed Discussion --
&& .NEAR TERM /TODAY AND TONIGHT/...
-- Changed Discussion --
AS OF 10 AM TUESDAY... OVERVIEW: POTENT UPPER LEVEL LOW WILL DRIFT NORTHWARD OVER THE CAROLINAS TODAY. SHORTWAVE ENERGY ROTATING AROUND THE UPPER LOW AND STRENGTHENING DIVERGENCE ALOFT UNDERNEATH AN UPPER JETLET ON THE EAST SIDE OF THE MID/UPPER LEVEL CIRCULATION CENTER WILL AID IN CYCLOGENESIS ALONG A COASTAL FRONT/INVERTED SFC TROUGH AS HIGH PRESSURE OVER THE MID-ATLANTIC WEDGES SOUTHWARD THROUGH CENTRAL AND WESTERN PORTIONS OF THE CAROLINAS. PRECIPITATION: PRECIP STARTING TO FAN NORTH OUT OF SOUTH CAROLINA IN THE NICE UPPER DIFFLUENCE PATTERN SHOWING UP ON WV IMAGERY. THIS PRECIP SHOULD REMAIN LIGHT THROUGH THE DAYLIGHT HOURS...WITH A TENDENCY TO DRY UP/DISSIPATE AS IT ADVANCES NORTHWARD INTO THE PIEDMONT AS IT ENCOUNTER DRIER AIR TO THE NORTH WHILE BECOMING FARTHER REMOVED FROM THE LOW-LEVEL EASTERLY ONSHORE FLOW. WILL CARRY LOW-END LIKELY POPS ACROSS THE SANDHILLS/SOUTHERN COASTAL PLAIN...DECREASING TO SLIGHT CHANCE INTO THE WESTERN PIEDMONT WHERE PRECIP WILL LIKELY BE OF THE NON-MEASURABLE VARIETY. PRECIP AMOUNTS WILL REMAIN LIGHT. PRECIP/LIFT WILL START TO CRANK UP LATE TONIGHT/TUESDAY MORNING WITH INITIAL SHARPENING OF THE INVERTED COASTAL TROUGH AND LOW PRESSURE WAVE DEVELOPMENT. RESULTANT ENHANCED ATLANTIC TRANSPORT/ISENTROPIC LIFT INLAND WILL YIELD INCREASING POPS AFTER MIDNIGHT WITH MOTORISTS EAST OF THE TRIANGLE EXPECTED TO CONTEND WITH A WET MORNING COMMUTE INTO WORK. EXPECT A SHARP CUT-OFF IN POPS AND QPF WEST OF THE TRIANGLE WITH RAINFALL AMOUNTS THROUGH TUESDAY MORNING RANGING FROM A THIRD OF AN INCH OVER THE SOUTHEAST TO NEAR A TENTH ACROSS EASTERN PORTIONS OF THE TRIANGLE. TEMPS: SHROUD OF GRAY OVERCAST SKIES MIXED IN WITH SOME LIGHT RAIN/SPRINKLES AND A STEADY 10KT NELY BREEZE...WILL KEEP TEMPERATURES ON THE CHILLY SIDE. HIGHS 65 TO 70. LOWS TONIGHT IN THE MID 50S NORTHWEST TO NEAR 60 EAST.
-- End Changed Discussion --
&& .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 255 AM TUESDAY... FORECAST UNCERTAINTY REMAINS ABOVE AVERAGE AS MODEL GUIDANCE CONTINUES TO HAVE DIFFICULTY IN CAPTURING THE PRECISE EVOLUTION OF A STALLED UPPER LEVEL LOW OVER THE SOUTHEAST CONUS...AND WITH PRECIPITATION ALONG THE SOUTHEAST COAST. THE LATEST GUIDANCE IS SIMILAR IN NATURE TO PREVIOUS GUIDANCE...SHOWING THE BEST POTENTIAL FOR RAIN ALONG/EAST OF HWY 1 DURING THE DAY WEDNESDAY AS A WAVE OF LOW PRESSURE ATTENDANT SHORTWAVE ENERGY ROTATING AROUND THE DEAMPLIFYING UPPER LEVEL LOW TRACKS NORTHWARD ALONG A RETROGRADING COASTAL FRONT. THE PRECISE TIMING/LOCATION OF SHORTWAVE ENERGY ROTATING AROUND THE UPPER LOW AND ULTIMATELY THE PRECISE TIMING/TRACK OF THE ATTENDANT WAVE OF LOW PRESSURE ALONG THE RETROGRADING (WESTWARD/INLAND MOVING) COASTAL FRONT IS DIFFICULT TO ASSESS...EVEN AT SHORT RANGE. QUALITATIVELY...EXPECT BROKEN TO OVERCAST CLOUD COVER EVERYWHERE AND AN INCREASING CHANCE OF RAIN FROM THE TRIANGLE EASTWARD TO THE COAST WITH TEMPS STRUGGLING TO EXCEED THE 60S. PRECIPITATION CHANCES SHOULD DECREASE FROM SW-NE WED NIGHT AS THE LINGERING UPPER LEVEL LOW BECOMES PROGRESSIVE IN RESPONSE TO STRENGTHENING SOUTHWESTERLY FLOW ALOFT IN ADVANCE OF SHORTWAVE ENERGY TRACKING EASTWARD FROM THE CENTRAL PLAINS INTO THE WESTERN OH VALLEY...THOUGH THIS FEATURE ITSELF IS EMBEDDED IN WEAK STEERING FLOW AND EXPECTED TO CUT-OFF OVER THE CENTRAL MS RIVER VALLEY WED NIGHT/THU...INTRODUCING MORE UNCERTAINTY THAN WOULD OTHERWISE BE THE CASE. ONCE AGAIN...EXPECT LITTLE DIURNAL VARIATION IN TEMPS WITH LOWS IN THE 50S/60S. WIND: THE MSLP/HEIGHT GRADIENT WILL TIGHTEN OVER CENTRAL NC WEDNESDAY...BETWEEN STRONG HIGH PRESSURE TO THE NORTH AND A DEVELOPING LOW PRESSURE SYSTEM ALONG THE CAROLINA COAST...AND FCST SOUNDINGS SUGGEST LOW-LEVEL NORTHEAST FLOW AS STRONG AS 30-40 KT. SHALLOW MIXING ASSOCIATED WITH LOW-LEVEL COLD ADVECTION WILL BE ENHANCED BY PRECIPITATION /EVAP COOLING/ ON WED...ESP IN THE SE COASTAL PLAIN WHERE A TIGHTER MSLP GRADIENT WILL BE JUXTAPOSED WITH HEAVIER PRECIPITATION. WITH THE ABOVE IN MIND...AREAS SOUTH AND EAST OF THE TRIANGLE COULD SEE A PERIOD OF BREEZY NORTHEAST WINDS GUSTING AS HIGH AS 30-40 MPH DURING THE DAY WED. KEEP IN MIND THAT THIS WOULD BE A WORST-CASE SCENARIO AND THAT WIND OF THIS MAGNITUDE WOULD FALL SHORT OF WIND ADVISORY CRITERIA...THOUGH PERHAPS CAPABLE OF A FEW DOWNED TREES IN THE PRESENCE OF HEAVY PRECIPITATION. -VINCENT && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 330 AM TUESDAY... SOME DRYING MAY BEGIN SOONER THAN PREVIOUSLY EXPECTED AS THE MID/UPPER LOW AND ASSOCIATED SURFACE TROUGH SHOULD BE QUICKER TO EXIT. AT LEAST SOME RESIDUAL CLOUDINESS IS EXPECTED THURSDAY AS THE SURFACE WAVE MOVES SLOWLY UP THE MID-ATLANTIC COAST...WITH CLEARING IN THE LEE OF THE MOUNTAINS SPREADING SE DURING THE DAY. THE NEXT CHANCE OF RAIN SHOULD COME EARLY NEXT WEEK. HOWEVER... MODELS CONTINUE TO SHOW PLENTY OF DISAGREEMENT. ALL IN ALL...TEMPERATURES SHOULD TURN MILDER LATE WEEK AS THE CLOUDS DEPART. HOWEVER...THE PROLONGED NE FLOW COURTESY OF HIGH PRESSURE TO OUR NE WILL KEEP READINGS IN CHECK. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 700 AM TUESDAY... 24-HR TAF PERIOD: EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE TAF PERIOD WITH CEILINGS GENERALLY NO LOWER THAN 5-8 KFT AND A NORTHEAST BREEZE AT 10 KT...EXCEPT 15 KT AT THE FAY TERMINAL LATER TODAY INTO TONIGHT AS THE MSLP GRADIENT TIGHTENS ALONG THE SOUTHEAST COAST. ANY CHANCE FOR SUB-VFR CONDITIONS SHOULD BE CONFINED TO THE FAY/RWI TERMINALS AT THE END OF THE TAF PERIOD WHEN PRECIPITATION AND MVFR CEILINGS MAY SPREAD INLAND IN ADVANCE OF A WAVE OF LOW PRESSURE TRACKING NE ALONG THE FRONTAL ZONE STALLED IN VICINITY OF THE SE COAST. LOOKING AHEAD: SUB-VFR CONDITIONS ASSOC/W RAIN WILL BE POSSIBLE AT THE RDU/FAY/RWI TERMINALS ON WEDNESDAY AS THE AFOREMENTIONED WAVE OF LOW PRESSURE TRACKS NORTHWARD ALONG THE MID-ATLANTIC COAST...THOUGH UNCERTAINTY PERSISTS WITH REGARD TO HOW FAR WEST PRECIPITATION WILL DEVELOP AND THE RELATIVE BEST CHANCE FOR SUB-VFR CONDITIONS WILL BE AT THE FAY/RWI TERMINALS. OTHERWISE...EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE REMAINDER OF THE WEEK AS HIGH PRESSURE EXTENDS INTO THE CAROLINAS FROM THE NORTH. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...CBL SHORT TERM...VINCENT LONG TERM...PWB AVIATION...VINCENT

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.